1. Field of the Technology
The illustrative embodiments relate to portable game machines and, more specifically, to a portable game machine including two or more display units, on each of which a three-dimensional game image, generated by a three-dimensional image processing unit, is displayed.
2. Description of the Background Art
Conventionally, in order to enhance a display screen area by using a plurality of display units, a computer system as disclosed in Japanese Patent Laid-Open Publication No. 2001-67054 (hereinafter referred to as a patent document) has been suggested. Specifically, as shown in FIGS. 6 and 7 in the patent document, this computer system includes two graphic engines in order to display images on two display units. Furthermore, each graphic engine includes a 2D engine for generating a two-dimensional image and a 3D engine for generating a three-dimensional image. This makes it possible to simultaneously display a three-dimensional or two-dimensional image on each of the two display units.
Also, it is known that a dual monitor system can be achieved by inserting two graphic cards or a single graphic card, having incorporated therein two graphic engines, in personal computers or the like, thereby simultaneously displaying three-dimensional or two-dimensional images on two display units.
In the above-described conventional technology, in order to display different three-dimensional or two-dimensional images on two display units, a graphic engine including a 2D engine for generating a two-dimensional image and a 3D engine for generating a three-dimensional image has to be provided for each display unit.
Here, portable game machines including two display units have also been suggested in order to enhance a display area. In such portable game machines, it is desired that a three-dimensional image is displayed on each display unit. However, portable game machines are required to be power-thrifty, small in size, and inexpensive. Therefore, it is not preferable to directly apply the above-described conventional technology to portable game machines. Reasons for this are specifically described below.
The 3D engine is required to perform complex coordinate calculations, and therefore is significantly larger in circuit size than the 2D engine. Therefore, providing two 3D engines corresponding to two display units invites an increase in power consumption, an increase in heating, an increase in the area of a semiconductor chip on which the 3D engine circuit is mounted, and an increase in cost. The increase in power consumption hastens exhaustion of a battery, thereby requiring frequent battery replacement by a player. The increase in heating requires a large housing for heat dissipation, thereby making it more difficult to easily carry the portable game machine. For these reasons, providing a plurality of 3D engines to the portable game machine may be ideal, but is not realistic.
Moreover, the computer system is provided with a selector for switching between the two graphic engines. Here, consideration is given below to whether three-dimensional images can be simultaneously displayed on two display units by using either one of the graphic engines to generate a three-dimensional image and then using the selector to select a destination to which the generated three-dimensional image is to be output. In this case, while an output from a single graphic engine is being supplied to one of the display units, no outputs from that graphic engine are supplied to the other display unit. In general, display units typified by LCDs and CRTs are configured to update a display screen at intervals of 1/60 seconds, and their graphic engine generates three-dimensional images of 60 frames per second for output. Therefore, If the three-dimensional images generated by the graphic engine are output alternately to two display units, each display unit is temporarily in a blank state for each frame, causing noticeable flicker on the display screen to the user.
Therefore, an feature of an illustrative embodiment is to provide a portable game machine capable of simultaneously displaying different three-dimensional images on two display units by using a single three-dimensional image processing unit without causing flicker on display screens.
Also, another feature of an illustrative embodiment is to make it possible for a portable game machine to include two display units, at least one two-dimensional image processing unit, and a single three-dimensional image processing unit, wherein a game image generated by the two-dimensional image processing unit is displayed on one of the display units and a game image generated by the three-dimensional image processing unit is displayed on the other display unit, and to simultaneously display different three-dimensional game images on the two display units without adding another three-dimensional image processing unit or substantially changing the configuration of the portable game machine.
An illustrative embodiment adopts the following structure to achieve the object mentioned above. Note that reference characters and numerals in parentheses below merely show examples of correspondence with the embodiment described further below for the sake of better understanding of the exemplary embodiment presented herein, and do not restrict the scope.
A first aspect of an illustrative embodiment is directed to a portable game machine including: a first display unit (11); a second display unit (12); a three-dimensional image processing unit (31); a capture circuit (33); a storage unit (21); a two-dimensional image processing unit (37); and an output destination setting circuit (35).
The three-dimensional image processing unit generates a first game image based on three-dimensional model data for each frame. The capture circuit captures the first game image generated by the three-dimensional image processing unit as two-dimensional image data. The storage unit stores the two-dimensional image data captured by the capture circuit. The two-dimensional image processing unit generates a second game image based on two-dimensional image data in a previous frame already stored in the storage unit. The output destination setting circuit (35) sets one of the first display unit and the second display unit as an output destination of the first game image and another one of the first display unit and the second display unit as an output destination of the second game image.
According to a second aspect of an illustrative embodiment based on the first aspect, in an n-th frame, the first game image generated by the three-dimensional image processing unit is output to the first display unit and is simultaneously captured, and the second game image captured in an (n−1)-th frame and based on the two-dimensional image data is output to the second display unit. In an (n+1)-th frame, the first game image generated by the three-dimensional image processing unit is output to the second display unit and is simultaneously captured, and the second game image based on the two-dimensional image data and captured in the n-th frame is output to the first display unit.
According to a third aspect of an illustrative embodiment based on the first aspect, the portable game machine further includes a first line buffer (32) for temporarily storing data for one line of the first game image generated by the three-dimensional image processing unit. The data for one line stored in the first line buffer is sequentially output to one of the first display unit and the second display unit, thereby eventually outputting an entirety of the first game image to the one of the first display unit and the second display unit. The capture circuit sequentially captures the data for one line stored in the first line buffer, thereby eventually storing the entirety of the first game image in the storage unit.
According to a fourth aspect of an illustrative embodiment based on the third aspect, the storage unit includes a first storage area (21a) and a second storage area (21b). Also, the portable game machine further includes: a second line buffer (38); a first selector (34); a second selector (36); a third selector (35); and a control unit (23). The second line buffer temporarily stores data for one line of the second game image generated by the two-dimensional image processing unit. The first selector switches an output destination of the capture circuit between the first storage area and the second storage area. The second selector switches an output destination of the two-dimensional image processing unit between the first storage area and the second storage area. The third selector switches an output destination of the first line buffer and an output destination of the second line buffer between the first display unit and the second display unit. The control unit controls a time of switching of each of the first selector, the second selector, and the third selector.
According to a fifth aspect of an illustrative embodiment based on the first aspect, the storage unit is provided with storage areas that correspond to at least two virtual screens (21c, 21d) to be used when the two-dimensional image processing unit generates the second game image. The capture circuit outputs the captured game image alternately to the storage areas in the storage unit that correspond to the two virtual screens. The two-dimensional image processing unit outputs one (21c) of the two virtual screens to the first display unit and another one (21d) of the two virtual screen to the second display unit.
According to a sixth aspect of an illustrative embodiment based on the first aspect, the three-dimensional image processing unit alternately generates and outputs, for each frame, game images representing two different states of a different virtual three-dimensional game space.
According to a seventh aspect of an illustrative embodiment based on the first aspect, the three-dimensional image processing unit alternately generates and outputs two different game images representing a state of a single virtual three-dimensional game space captured by a virtual camera with two different settings (FIG. 6).
An eighth aspect of an illustrative embodiment is directed to a computer-readable storage medium having stored therein a program causing a computer connected to a display unit to function as: display means, three-dimensional image processing means, capture means, storage means, two-dimensional image processing means, and output destination setting means.
The display means causes the display unit to display a first screen and a second screen. The three-dimensional image processing means generates a first game image for each frame based on three-dimensional model data. The capture means captures the first game image generated by the three-dimensional image processing means as two-dimensional image data. The storage means stores the two-dimensional image data captured by the capture means. The two-dimensional image processing means generates a second game image based on two-dimensional image data in a previous frame already stored in the storage means. The output destination setting means sets one of the first display unit and the second display unit as an output destination of the first game image and another one of the first display unit and the second display unit as an output destination of the second game image.
A ninth aspect of an illustrative embodiment is directed to a computer-readable storage medium having stored therein a program to be executed in a portable game machine including: a first display unit (11); a second display unit (12); a three-dimensional image processing unit (31); a capture circuit (33); a storage unit (21); a two-dimensional image processing unit (37); and an output destination setting circuit (35).
This program causes a computer (23) of the portable game machine to perform steps including: in an n-th frame, a step (S31, S32) of causing the three-dimensional image processing unit to generate the first display image; a step (S36) of causing the capture circuit to capture the first display image; a step (S39) of causing the two-dimensional image processing unit to generate the second game image based on two-dimensional image data captured in the n-th frame; and a step (S15) of causing the output destination setting circuit to set the first display unit as the output destination of the first game image and the second display unit as the output destination of the second game image.
Also, this program causes the computer of the portable game machine to perform steps further including: in an (n+1)-th frame, a step (S51, S52) of causing the three-dimensional image processing unit to generate the first display image; a step (S56) of causing the capture circuit to capture the first display image; a step (S59) of causing the two-dimensional image processing unit to generate the second game image based on two-dimensional image data captured in the n-th frame; and a step (S19) of causing the output destination setting circuit to set the second display unit as the output destination of the first game image and the first display unit as the output destination of the second game image.
According to a tenth aspect of an illustrative embodiment based on the ninth aspect, the three-dimensional image processing unit generates game images representing a virtual three-dimensional game space viewed from a first view point and a second view point that are different from each other. Also, the program causes the computer to performs the further steps of: causing the three-dimensional image processing unit to generate, in the n-th frame, a first game image based on the first view point; and causing the three-dimensional image processing unit to generate, in an (n+1)-th frame, a first game image based on the second view point (FIG. 6).
According to the first aspect, when the first game image generated by the three-dimensional image processing unit is output to the first display unit (or the second display unit), the image of the previous frame captured by the capture circuit is output to the second display unit (or the first display unit). With this, by using a single three-dimensional image processing unit, a three-dimensional game image can be displayed on two display units.
According to the second aspect, the first game image generated by the three-dimensional image processing unit is output alternately to the first display unit and the second display unit. With this, by using a single three-dimensional image processing unit, a three-dimensional game image can be displayed on two display units. Also, a display unit that is not supplied with the first game image is supplied, via the second-image processing unit, with the first game image captured in the immediately-preceding frame by the capture circuit for display. Therefore, no flicker occurs on the display screen. Also, the image on each display unit is updated once in a two-frame period. Therefore, a moving game image can be smoothly displayed.
According to the third aspect, the first game image generated by the three-dimensional game processing unit is output via a line buffer to a display unit. Therefore, compared with the case where a frame buffer is provided between the three-dimensional image processing unit and the display unit, the size and cost of the portable game machine can be reduced.
According to the fourth aspect, the first selector, the second selector, and the third selector control the control unit as appropriate, thereby causing the portable game machine to easily performing the operation according to the first aspect.
According to the fifth aspect, the first game image captured by the capture circuit is stored in the storage unit as two-dimensional image data for two virtual screens to be originally used when the two-dimensional image processing unit generates a second game image. Therefore, a storage area for temporarily storing the captured first game image is not additionally required, thereby reducing the cost of the portable game machine. Also, a function of outputting the image corresponding to one of the virtual screens is a function originally provided to the two-dimensional image processing unit. Therefore, no special function is additionally required in the two-dimensional image processing unit. A function of switching among a plurality of virtual screens for display is a function originally provided to the two-dimensional image processing unit.
According to the sixth aspect, by using a single three-dimensional image processing unit, different states of the virtual three-dimensional game space can be displayed on two display units.
According to the seventh aspect, by using a single three-dimensional image processing unit, states of the virtual three-dimensional game space captured by the virtual camera with different settings can be displayed on two display units.
These and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.